Add the empty Rust workspace

Three stub crates following Odin's layout: huginn-mind and eureka-state as
libraries, huginn-daemon as the binary. Edition, license and publish are
workspace-owned. .gitignore gains target/ and drops the four entries that
named build outputs no longer produced here.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

Cargo.toml

@@ -0,0 +1,12 @@
+[workspace]
+members = [
+    "crates/huginn-mind",
+    "crates/huginn-daemon",
+    "crates/eureka-state",
+]
+resolver = "3"
+
+[workspace.package]
+edition = "2024"
+license = "MIT"
+publish = false